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Closed v. Open (Bolt)

What, if any, scientific explaination is there for the effects of a closed bolt versus an open bolt on a paintball's accuracy?

A lot of people have bought into the WGP's advertising of a cocker being more accurate gun that gets better distance. I am aware that distance is determinded by velocity, and accuracy is mainly determined by the barrel and paint. But could other factors in the gun play into these, and if so, how?

one thing that the closed botl gns do have is less blowback, but they also feed slower so its a plus and a minus. I will only shoot a closed bolt gun personally. I understand that there is almost no reason for it. But my cocker shoots straighter than my mag with the same paint to barrel match as my mag. I dont know why i dont care why. it does.

my 2c....

Accuracy is also determined by the "pre-coil" and "recoil" of the gun. Meaning if there is a lot of jump to the gun right before it shoots it will be less accurate. When there is a lot of recoil it will lead to an inaccurate second shot, third, and so on (in rapid fire). On cockers since only a hammer moves before the shot there is little precoil so it is considered accurate.

Also if you were to eliminate any reciprocating weight in the gun when firing it will increase accuracy. ie. using delrin, teflon injected nylon, or milling or turning down on internals like bolts and valves.

in an unrealistic enviroment, where recoil does not matter, accuracy is not effected. in real life, the recoil can make a slight difference, but not very much. the delrin bolts should take care of some of the problem with the mags recoil...

IMO...

What I have also noticed...

When a ball is in a chamber of an Open bolt gun and that chambers diameter is larger then .69'' the ball will litterly have to "jump" up into the breech of the barrel. This will cause a slight forward spin... BAD. It is hard to notice but ask angel owners about a slight hook they are incountering (angel breeches are big). I thought my theory would be wrong but then I heard about 12-15 people talking about it on the pbnation.com forum.

After that to only thing that can affect accuracy is gas disturbation on the ball. Not too many guns have this prob.

This jump is exactly why 'Mag work by dropping the ball directly into the barrel. This is also the reason do not like the Freak Barrel system, since the "back" is a very large bore that you put inserts into there will *always* be that jump.

Nice discussion here guys. Yes lets say that reciprocating weight does have an effect on recoil and gun movement. Then by that thinking a heavy gun would be at an advantage because it's greater mass would move less. Do you see any accuracy difference between light an heavy markers?

AGD

ps someone measure the weight of a cocker hammer and rod and a Superbolt.

Sounds about right...

But who would want to add more weight? The only other thing you can do is have something move in the opposite direction of the origional reciprocating weight to cancel out the movements.... Seems not worth it just to eliminate a bit of recoil- not to mention things that could go wrong with the device.

You are better off finding a way to move less parts in a gun with light parts. NOT EASY. I managed to get an amazing Impulse hammer mod that takes off a lot of recoil. Still ave a little "jump" into the barrel but I'm not about to drop 500$ for a new Body to turn it into a mag type barrel.

Re: Sounds about right...

Originally posted by Jonny05 ... hold the gun tighter. Seriously it works.

I'm with ya there. I have to have a shoulder "stock".

As far as open vs closed , way back before the automag there were basically two different types of semi auto paintball guns. There were the closed bolts (one by Glenn Palmer and one by Bud Orr) and open bolt blow back guns. The blow back guns had the bolt attached to the hammer. When you fired the gun the hammer shoved the bolt forward driving the paintball into the barrel and then cracking open a valve to fire the gun. Considering the consistency (or lack thereof) of paintballs the force required to shove the paintball into the barrel would be different. Since the hammer was attached to the bolt the force with which the hammer struck the valve would also be different, causing inconsistent velocities. Also, the moving parts were heavier, causing more precoil/recoil (ie, the gun moved more). At least, that was the prevailing theory at the time.

Well not necessarly...

Paint is 10-15% of accuracy.
Gun precoil (varies with weight and moving parts) is 10-15%
Jump is 5-10%.
Gas dynamics is 2-5% of it.
Barrel is 30-40% of it.

That is completely random but you get the idea. To actually get a test you would need lots of time and money. Back to the point-> BY MAKEING A GUN HEAVIER YOU WONT CURE TE OTHER PROBLEMS. It may in fact hinder your play.

**other factors like ball detents and recoil are not even taken into consideration**

CLOCKWORKERMILLER-Ball jump or forward roll is something I thought of when making a few custom angel bolts (realizing the larger diameter). I figured it wouldn't have any effect but I watched many people talking about it. So many with different bolts, barrels, gas systems, paint, etc. Still one factor is the same in all cases... the 18mm chamber (big trip on barrel lip).

I have friends too but...

You would have to eliminate the other factors to test for each catorgy.

For ball jump you would have to use the same air system, paint, barrel (check with dial indicator), and clamp down the guns so the precoil doesn't count. Changing up bolts would help too. Like I said... It would take some connections and money.

The paint would have to be two coloured and place in so you may see if there is any spin. It would have to be indoors and with a lot of paint.

Any opinion that isnt based on factual evidence is an uninformed, and poorly supported opinion.

Im just saying, the easiest way to test it would be take two guns, give them the same barrel, the same paint, and same air system, same regulator, and then have at it.

If you put a case through each gun, then any small inbalances would be negated, and the only factor that should effect accuracy would be the bolt, whether it is closed or open.

Personally, I think there is a difference, but it is such a minimal difference that it would have no bearing in a fire fight. Thats based on the tests I've seen. I would like to see it between difference guns.

somebody came out with a new electro kit for a cocker, which lets the marker operate in both open and closed bolt. it will be interesting to see how many people buy this upgrade just to see if closed bolt really is better.

The ppl that make the new electropnematic cocker upgrades also make the mayhem.. can't recall the company name. I am gonna post what I said in IRC earlier today.. doesnt have much to do with the discussion, but.. well.. :
"To me, Bud Orr isn't innovative.. *POOF*

There is another comparison to make with the barrel jump scenario. Real handguns kick like a mule and jump several inches, by the same thinking they should not be able to hit ANYTHING! So why ARE real handguns accurate? Good Deep Blue question, answer that and you will know the answer to paintball gun kick vs accuracy.

Why handguns are accurate...

The reason that handgun jump has little effect on handgun accuracy is simple: the bullet is traveling so fast that it leaves the barrel before the barrel jumps due to recoil.

As far as open bolt versus closed bolt, there is only ONE reason the cocker is a closed bolt gun: it is based off the Sniper pump gun. So, instead of being a semi-auto in the traditional sense, it is in fact a pneumatically pumping pump gun. Also, any movement caused by the mag bolt loading the ball into the chamber is negated by the barrel. As far as accuracy goes, (barring spin), the barrel is the great equalizer of paintguns. Once into the breech(sp?), then it's fair game as far as the paintball is concerned.

I have an idea about being able to swap the same barrel on to different guns what about a diablo matrix which is closed bolt and say an angel(the only reason I suggested that is because they don't make automag breeches)the only thing you have to do with a matrix is change the breech and you can put on just about any barrel you want from spyders to autocockers.

Obstacles are what you see when you take your eyes off of your Objective.

Well being a converted pump isnt the only reason for a cocker to be closed bolt. i personally have made an open bolt cocker. Switch the 3 way hoses then timed it differently. So there is a small advantage to having it closed i gaurentee it.